People do read the DMG. It's organized like crap though.It is necessary to reiterate what @payn already said- apparently, no one reads the DMG.
And if your DMG is put together as a rush job, some of the variants that are used to patch the system should have been either core rules or placed front and center to create more uniformity amongst the community.
Because I don't have the problem as a DM. I'm experienced. The problem is as a player. Being a DM of 5e has made me critical as a player. I have the urge to grill the DM on which variant rules they are using. Because as written core 5e like many games has wonky bits that require variants and houserules if they bother you.
I can't blame DMs for not finding these variants because the DMG is organized poorly.
Because if your DMG is disorganized and vague, you can't be shocked that the majority of the fanbase doesn't read it If you put out that kind of DMG, your core rules oughta be more sturdy.